Here’s a quick tip that may help you with getting over white water.
When I’m in my four man surfing canoe and we’re paddling back out through the surf, as we approach a white water, there are basically two things we try to do. One, pick up a little extra speed on the approach, and two keep paddling right through the white water. The same is true for stand up. On the last five strokes prior to hitting the white water, pick it up a little to maximize your inertia that will help carry you over it. Next, and this is where most people make their mistake, keep paddling through the white water (or at least take a stroke) as the nose of the board initially hits it, in order to pull yourself through the first part. This serves two purposes, it will help get you over the initial climb and two, your blade will be in the water already to act as a stabilizing device in case the white water is trying to knock you off. What you don’t want to do is raise your paddle high, which I see people do all the time.
The next little key to success is to move your normal back foot back slightly just before impact, this will help create a little extra stability. Meaning if you are regular footed in your surf stance, then move your right foot back prior to impact and vice versa if your a goofy foot. How much you move that foot back is dependent upon how big the white water is. Ankle to knee high white water and I will move it back maybe six inches to a foot. Knee to waist, a foot or two, and head high and over I will move that rear foot back at least two to three feet. One of the main reasons to move the foot back is to shift your weight back slightly so that the nose of the board will be elevated as it meets the front of the white water. The trick becomes moving your weight back over your front foot just after impact to aid the board in climbing over it. If you stay on your back foot to long it will usually end in popping a wheelie and then flying out the back door. It also helps if you can have the paddle on your front side, meaning your right side for regular stance and your left for goofy.
I hope this helps and good luck.